Stanford envisions 'all-electric highway' that charges EVs as they go

Readers of a certain age may remember the 1982 hit "Electric Avenue" by Eddy Grant. Now, Stanford University is putting its own spin on the concept.

The school says it's developing a technology that would allow electric-drive vehicles to be recharged as they're being driven down the road. The system involves magnetic energy being sent between metal coils placed in the road a few feet apart.

The process, called "magnetic resonance coupling," involves tuning the road coils and a coil at the bottom of a car to the same natural frequency, so that, when the road coils are charged with an electric current, they send electricity to the coil in the car, which then recharges a battery. Ultimately, Stanford researchers say they can develop what's essentially an electric highway that one of the researchers said may give an EV a higher charge after driving than before the trip started. Imagine that.

Obviously, such technology is a long way off being used by consumers, but the concept of wireless electric charging is a topical one because what's perceived by some to be the inconvenience of having to use a cord to recharge a vehicle. Indeed, global consumers may spend as much as $1.5 billion in wireless EV chargers by the end of the decade, Pike Research said in a 2010 study. Companies like U.S.-based Evatran and UK-based HaloIPT have developed in-ground wireless charging systems that allow EVs to be recharged by merely being parked on top of a charging system. Last week, Hertz said it would be the first rental-car company to test a wireless recharging system – made by Evatran – on its vehicles.

Moreover, an all-electric highway like the one pitched by Stanford would address the even larger issue of "range anxiety," since production EVs such as the Nissan Leaf currently provide for an official 73 miles of single-charge range. Last summer, researchers at Utah State University said they were able get get five kilowatts of electricity to jump an air gap of up to ten inches at 90 percent efficiency, implying that they were in the early stages of working on a similar "electric highway."

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.

Interesting research. Idea's like these are always worth researching, especially for new highways and roads. It could be an excellent method of revenue for the owner of the highway, especially as an incentive for privatised road operators. This concept may reduce the need for the concept of an EV mileage tax. But, like many great ideas, the feasibility and logistical practicalities are a long way from realisation. But, it good to know that research like this is progressing.

If you could charge at a higher rate than your car needs to keep moving then they could reduce the amount of roadway that would need to be modified to include this energy transfer system. Idealy they could design the system so that it would only charge vehicles when they are traveling uphill which is when a car requires the most power to maintain an acceptable speed. And hopefully in the future "Intelligent Cruise Control" will allow the vehicle to slow slightly on major inclines which will improve efficiency and lengthen charging opportunity time.

Anonymous

3 Years Ago

The concept of wireless charging is great, though it does have a few detractors. First, are all these EVs capable of wirelessly charging using a standard or are they each a different spec? Second, how reliable are the systems in sub-optimal conditions (rain, snow, ice, etc)? Third, how do they track which vehicles are getting how much of a charge? This is key in setting up payment for the electricity, otherwise you are stuck using a default billing schedule where you have to measure each EVs mileage per year and charging upon that.

Hey Rex, I don't know a ton about this technology, so I'm admittedly talking out of my a$$, but... 1. Standards I imagine will be a big deal, and will likely be the thing to keep this from happening anytime soon since public roads would need government involvement, and we all know how that works... 2. I would imagine that most weather conditions would have little effect on magnetic coupling, unless there was an electro-magnetic component to the weather (ie lightning). 3. Tracking I would imagine be toll based, much like eazy-pass/fast-pass systems in so much as there would have to be some wireless communication and tracking by the car itself or onboard system (ie the highway doesn't keep track, your car does...)

As for #2, I'd also be concerned about road salt use in the Northern states. Salt corrosion and freeze/thaw cycles can wreak havoc on an electric grid installed under the pavement. In any case, I'm wondering if the long-term movement through an electric field strong enough to recharge a car might interfere with other electronics within a car.

Anonymous

3 Years Ago

@methos1999

My questions were mostly rhetorical, more so meant to cause discussion. 1. Yes, standards will be key to any implementation. Without a standard, I don't see anyone making the jump any time soon. 2. Indeed, there shouldn't be any major issues aside from a drop in efficiency in most weather issues. What about weather cause aging of the roadway? This is more a concern for asphalt roads as they are more prone to aging issues (potholes, cracks, settling and sagging). This can be quite an issue here in Colorado, especially so for mountain highways. 3. Some of the costs may be offset by gov incentives, namely relating to construction and if the roads were planned correctly much of the electricity could be potentially supplied by wind, solar, and maybe geothermal. I would assume that the charge controller of the car collects the data and relays it via wireless (cell, radio, or wlan).

Wow, we can't afford to fix the bridges we have today that are falling apart and we can't patch the potholes in most northern states....but we're going to put this under a major portions of American roads??? This is really silly. Maybe Newt will back it for us LOL

you are right!!!!!there isn't 'politics' anymore In US..here is big oil and corporations and there are actual humans who need clean water and a stable climate and affordable food and decent health coverage and jobs which add value and a purpose in life besides me me me greed baby greed. and I am aware denialists dont believe in anything but god of hate, but potholes etc as most cities are bankrupt will get worse and worse due to freeze thaw cycle and more and more extreme temp shifts..so owning a car like owning a home in america now where you pay for ALL the costs of climate change in form of increased prop taxes increased prop insurance mandatory flood insurance and when all families move away due to fracking and from being repeatedly flooded along with businesses who CAN move, you are stuck as well, from a cost benefit analysis, is not even worth it at all. super rich now just rent...they aren't stu*(d either..... it is why the whole unsustainable 'economy; is akin to rats jumping off a sinking ship. whoever can opt out IS opting out. but where to go? to the 'sun belt' where they already have no water and people are too brainwashed to 'notice' it???? speaking tactfully, it is going to be very interesting times. Israel already openly states it is going to 'respond' to fake false flag events it orchestrated itself....and Iran has already cut off oil to most EU since it is self sufficient and is TRYING to use clean energy.... why is US attacking pakistan non stop which is a semi failed stated which has had nukes for a decade now??? we dont seem to be too concerned there. re: climate change, it is NOTnew by the way. greenhouse gas emissions were mentioned in 1860 in scientific literature from coal emissions. only in THIS country is actual science still 'debatable' even evolution etc...at this point we are devolving so fast, eventually people will be stu*(id to know difference anyway....or even spell evolution. also on top of local roads turning to sh*( every day now is trying to stop fracking, trying to stop local right wing tea party from cutting all education funds....so kids who are not wanted have to be born who dont have a right to wait until they can have parents who can afford them; I believe in reincarnation not going to magic fairy land where I dont have to give a sh*( about future climate disaster created now like 'religious' in america... GOP's 'vision' for America: ensure US is 100% owned by big oil because GOP worship Saudi Arabia which now openly states it has no water at all due to using it all up!!!! Make sure we are controlled by right wing radicals as in a theocracy, who force unwed moms living in abject poverty to just pop out unwanted kids, ensure they have no education, no head start, no medical coverage, no safe food, no stable climate, no clean water and 'voila! you have the GOP 'workforce' of the future!!! would jesus frack his neighbor????? what fu(*ee up hateful skewed version of 'bible' do tea party read?

Anonymous

2 Years Ago

All this could possibly do is provide very cheep transportation for one large American city and cause a worldwide scarcity of copper! It matters not if the idea works, the WORLD cannot benifit from such a wasteful design.

There's another problem with this: the fear factor. The idea of transmitting large amounts of power wirelessly along a public road will surely ruffle some feathers. It's one thing for a customer who chooses to buy a wireless charger and install it in his home. It's very different, politically, to install this along a road that is used by all. Despite their wide use and general acceptance, some people have apprehensions about the possibility of cell phones or wireless routers causing cancer. Nobody wants high voltage power lines running over their backyard or a cell phone tower anywhere near their house, out of fear of unknown dangers. People get even more cautious when it involves a baby or prenancy. Would the technology be safe? Probably, but I don't know. Would enough people object to it for politicians to kill it? I'd take that bet.

We are barely able to afford to maintain our highways at this point; kind of funny to envision something like this during the global energy/economy decline. Induction charging is the worst because it wastes 10% energy and is expensive to implement as well. Autoblog; can you ever post some REAL advances in green tech.. like you know.. what green car congress does..

2WM: It appears that the cost of induction charging is 2-3% over that of wires, at least according to Evatran as I noted before. The 10% figure is total losses, most of which it seems are common to wired charging. Just the same I won't be betting heavily on electric roads anytime soon! ;-)

but it isn't an 'equal' decline...and actually other places are not declining at all....just like the 'debate' over scientific facts isn't global in nature...'pseudo' debate is ONLY in US and only due to TRILLIONS of big oil which is going to get worse in US due to four dollar gas which we have here already and which is going to keep going up as all of US foreign interevention/hegemony/'nation building' while attacking countries for oil is all backfiring...sanctions against a country trying to NOT use oil is now creating a regional superpower aligned AGAINST us....so much for trillions of barrels of oil wasted, lives, national wealth down the toilet for absolutely nothing!!!! and in fact our global wars for oil actually RUINED our global reputation which is now sh*() in most former 'allies'....other places are moving far far ahead of us...many countries have nationwide bike rentals, nationwide elec. car rentals, nationwide high speed rails, even nationwide elec .motorcycle rentals..walkable communties, bike trails etc. etc etc. and unlike US they are all powered by clean energy as well...climate catastrophes from what WE are doing is happening NOW....also 'peak oil' is here now, hence all the wars we are starting for oil...next will be wars for water..saudis admit they have no water. they still have a sh*( load of oil and guess what??? they haven't figured out how to drink it yet since oil and water don't mix. but in US it is correct we can't even fix our roads now...I think all developers in US need to start having to put up hitching posts when they build anything.....because it is almost impossible to drive anything BUT a tank anywhere anymore...but of course just ignore it and drive huge gas guzzlers and pretend absolutely nothing is happening at all anywhere ever...tea party campaign slogan: la la la la I cant hear your... US is greece!!! we are exactly the same and actually worse since we still affect rest of world...however we print dollars constantly...our deficit is going up, our total debt to rest of world keeps going up...politicians keep passing the buck, literally...even WHILE our infrastructure is going in the toilet..right wing keep tying climate catastrophe inducing 'riders' to any clean bill to ruin its' chance of passing, Obama keeps all his spending increases to 'balance' all the record low tax rates by GOP for their top 1% cronies.....wow, future is SO bright in US...be happy for ANY news...until tea party states BAN any 'green' news.

You're leaving out some data for a proper comparison. There is an energy cost of taking an AC input and converting the voltage to something higher. That is typically in the 10% - 30% range. Then there is a energy cost of the actual transmission during connection. You add that on top of the AC-DC conversion efficiency loss. With an appropriately sized wire connection, the additional loss will be less than 0.1 percent. All claims for inductive charging i have seen are anywhere from a 5 to 15 percent loss in the 'wire' part. I have not seen this 2-3% claim from any group. Another problem is that cars will want different voltages, so the inductive charging voltage will be fixed, and there will have to be a conversion on the car's end. If you feed 220v AC, then great. But you still have to eat the 10-30% AC-DC efficiency loss.

The question is how much of these losses are peculiar to induction charging, and how much are common to both that and plugging in. According to Nissan overall losses are about the same: 'Infiniti, launches its new EV model in 2014. Nissan says the charging system is 80-90 percent efficient depending on how well aligned the car is to the charging area. That’s about the same range, the automaker says, as a conventional (conductive) plug-in charger because of electrical losses between the plug on the car and the plug in the wall.' http://www.popularmechanics.com/cars/alternative-fuel/electric/2014-infiniti-ev-to-debut-wireless-inductive-charging-system And according to Daimler: 'Efficiency of the system admittedly still doesn´t match charging by cable, but is with 90 percent already very promising and only slightly beneath cable based solutions, if all components from socket to battery are taken into account.' http://green.autoblog.com/2011/12/05/daimler-testing-b-class-e-cell-with-inductive-charging/ According to Evatran the loss over the air gap is only 2-3%: 'From the wall to the car, Plugless Power's system is around 90-91 percent efficient, and the efficiency across the gap is an astonishing 97 percent. A year ago, the overall efficiency was just 80 percent.' http://www.green.autoblog.com/2011/08/01/plugless-power-getting-ready-for-real-wireless-chevy-volt-charg/ And on Evatran's site: 'The Plugless Power technology has achieved over 90% efficiency as measured from your home’s 208/240V electrical outlet to your vehicle’s existing on-board battery charger. This loss of efficiency, which is present in similar electrical devices, does not lead to increased charging times for your EV. Your vehicle will continue to recharge in the same amount of time needed by traditional corded methods, ' http://www.pluglesspower.com/questions-answers/technical-specifications/efficiency/ So there are certainly losses, but according to these sources much of them are common to wired charging, and the overall loss is certainly less than the total 10% loss, as that includes the losses which you would get anyway if you plugged in. The 2-3% I quoted is the figure for the loss over the air gap, which is the only loss I could identify as positively unique to inductive charging.

I'm quite sure an inductive charging link would have the ability to step up or down voltage in the one process just like a transformer so I can see DaveMart's point. I can't see how it could be as efficient as a cable either but it may well be freak circumstances to do with supply voltage compared to battery voltage and AC DC conversions. I'm still looking forward to hearing some decent explanations though. There is quite a bit to it and since we work with the voltages we already have the results may not be optimal. So if you consider a solar powered home which converts DC from the panels to AC through the inverter, then powering a charger and through and number of other steps getting DC in to the batteries again. Well that's a lot of steps and I'm not sure any of it is properly optimisied yet since EV's aren't exactly common and I doubt grid feed solar panel installations are designed with EV's in mind. I think there is a way to go before we see how it all pans out.

Daryl: I doubt that inductive is quite as efficient as wired charging, unless the latter were a very poorly designed one However, the losses are certainly below 10%, and from this approaching 2-3%, and so would seem to me to be acceptable. Everything is lossy, the question is how much and is the benefit worth the cost. I would answer yes for for inductive charging. I hasten to add though, that I am talking about regular use, not electric highways, which are blue sky research, worthwhile but not imminent.

It would be more efficient(and probably cheaper) to invest in high speed electric rail service which solves the problem of long range electric travel along heavily traveled routes. We will still need higher capacity batteries or fast charging to allow electric vehicles to drive to rural/remote locations.

supplemented by wind turbines along highways so all speeding cars also charge infrastructure...it would be awesome...I look forward to seeing it in reality in Europe and Asia where citizens like progress and not getting bent over by big oil while ruining your own climate and driving up food prices and having no water and having more disease... The only thing that denialists in Amerika love more than hating all other countries and everybody else and having an extremely narrow ideology they ascribe to so they can think they are somehow 'better' than _____ and trying to keep starting wars for oil/religion and having no food and no water and permanent drought and climate disasters like year round tornadoes and flooding..are these 'elitist' scientists actually trying to come up with global solutions!!!! yee haw!!!

I wonder how deep the line could be. It would either need to be below frost depth, or you would need to replace the subgrade with a geofoam like material that wouldn't be susceptible to heave. Ten inches sounds good, but that means multiple lanes would need these lines. Unless you just have a single charging lane. And depending on the charging quantity, you wouldn't need to have a continuous line. It may be possible, but there are definitely issues with such a plan.